<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .pink {
            background-color: aquamarine;
        }
    </style>
</head>
<body>
    <button class="pink">按钮1</button>
    <button>按钮2</button>
    <button>按钮3</button>
    <button>按钮4</button>
    <script>
        // 获取所有按钮
        let btn = document.querySelectorAll("button")
        for (let i = 0; i < btn.length; i++) {
            btn[i].addEventListener('click',function () {
            document.querySelector(".pink").className=''
            this.className='pink'
         })
        }
    </script>
</body>
</html>